So far, the Trump administration’s trade policy has seen an internal division among economic nationalists and “globalists” on the president’s senior staff. The economic nationalists, and the president himself, believe protectionism will strengthen the American economy. “Look at the 19th century,” said former White House chief strategist Steve Bannon in his recent “60 Minutes” interview. “What built America’s so called ‘American system,’ from Hamilton to Polk to Henry Clay to Lincoln to the Roosevelts? A system of protection of our manufacturing, financial system that lends to manufacturers, OK, and the control of our borders.”

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Mr. Bannon’s simple story is historically and economically off base. As Treasury secretary, Alexander Hamilton wanted moderate tariffs, not protectionist duties. In his day, tariffs accounted for nearly all federal revenue. He wanted to keep imports flowing so he could finance the federal government’s Revolutionary War debt and secure the young nation’s credit. President Polk, far from being a protectionist, was a small-government Democrat. He slashed tariffs dramatically in 1846....

Economic nationalists always conveniently skip the story of the 1930 Smoot-Hawley tariff, probably because it doesn’t fit their narrative. Smoot-Hawley—passed by Republicans and signed by a Republican president—didn’t cause the Great Depression, but the trade wars it inspired certainly damaged the world economy and backfired badly against the United States.

More important, America didn’t boom during the 19th century because it was a closed economy. The U.S. industrialized rapidly between 1833 and 1860, when tariffs were being cut. While tariffs were high after the Civil War, the U.S. was open to foreign capital inflows. It was also open to the best industrial technology from Britain and Germany, and—importantly given Mr. Bannon’s assertion that the U.S. had control of its borders back then—to massive immigration. The textile mills and steel furnaces of the late 19th century were largely staffed by foreign-born workers. As in our own era, many native-born Americans weren’t interested in doing tedious and grinding jobs at low wages....

The claim that protectionism made America’s economy great in the past, and can do so again today, is wrong. When the government boosts domestic steel prices to protect a few firms from foreign competition, it also hurts domestic steel users who need cheap inputs to remain competitive in a global marketplace. Making the U.S. a “high price island” for steel, semiconductors, sugar and solar panels favors some businesses at the expense of others. Protectionism can even push manufacturers to leave the country in order to remain competitive. And protectionism hurts exporters—not just the many American farmers who sell to foreign markets, but big manufacturers, such as Boeing and General Electric , which produce goods for sale abroad.